Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for active threat tracking and response. One of the methods includes determining, using sensor data generated by one or more sensors located at one or more properties, that an active threat is in progress at the one or more properties; accessing a virtual model i) of the one or more properties ii) that includes a position of each of the one or more sensors; determining, using the sensor data and the virtual model and for each of two or more areas of the one or more properties, a threat level of the active threat at the respective area; and performing, using the threat level of the active threat at each of the two or more areas of the one or more properties, one or more monitoring system actions.